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[linux-2.6/next.git] / drivers / watchdog / s3c2410_wdt.c
blobe4cebef55177f62e3067e0b2a7195f76ee03d725
1 /* linux/drivers/char/watchdog/s3c2410_wdt.c
2 *
3 * Copyright (c) 2004 Simtec Electronics
4 * Ben Dooks <ben@simtec.co.uk>
5 *
6 * S3C2410 Watchdog Timer Support
7 *
8 * Based on, softdog.c by Alan Cox,
9 * (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
24 */
25
26 #include <linux/module.h>
27 #include <linux/moduleparam.h>
28 #include <linux/types.h>
29 #include <linux/timer.h>
30 #include <linux/miscdevice.h>
31 #include <linux/watchdog.h>
32 #include <linux/fs.h>
33 #include <linux/init.h>
34 #include <linux/platform_device.h>
35 #include <linux/interrupt.h>
36 #include <linux/clk.h>
37 #include <linux/uaccess.h>
38 #include <linux/io.h>
39 #include <linux/cpufreq.h>
40 #include <linux/slab.h>
41
42 #include <mach/map.h>
43
44 #undef S3C_VA_WATCHDOG
45 #define S3C_VA_WATCHDOG (0)
46
47 #include <plat/regs-watchdog.h>
48
49 #define PFX "s3c2410-wdt: "
50
51 #define CONFIG_S3C2410_WATCHDOG_ATBOOT (0)
52 #define CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME (15)
53
54 static int nowayout = WATCHDOG_NOWAYOUT;
55 static int tmr_margin = CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME;
56 static int tmr_atboot = CONFIG_S3C2410_WATCHDOG_ATBOOT;
57 static int soft_noboot;
58 static int debug;
59
60 module_param(tmr_margin, int, 0);
61 module_param(tmr_atboot, int, 0);
62 module_param(nowayout, int, 0);
63 module_param(soft_noboot, int, 0);
64 module_param(debug, int, 0);
65
66 MODULE_PARM_DESC(tmr_margin, "Watchdog tmr_margin in seconds. default="
67 __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME) ")");
68 MODULE_PARM_DESC(tmr_atboot,
69 "Watchdog is started at boot time if set to 1, default="
70 __MODULE_STRING(CONFIG_S3C2410_WATCHDOG_ATBOOT));
71 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
72 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
73 MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, "
74 "0 to reboot (default depends on ONLY_TESTING)");
75 MODULE_PARM_DESC(debug, "Watchdog debug, set to >1 for debug, (default 0)");
76
77 static unsigned long open_lock;
78 static struct device *wdt_dev; /* platform device attached to */
79 static struct resource *wdt_mem;
80 static struct resource *wdt_irq;
81 static struct clk *wdt_clock;
82 static void __iomem *wdt_base;
83 static unsigned int wdt_count;
84 static char expect_close;
85 static DEFINE_SPINLOCK(wdt_lock);
86
87 /* watchdog control routines */
88
89 #define DBG(msg...) do { \
90 if (debug) \
91 printk(KERN_INFO msg); \
92 } while (0)
93
94 /* functions */
95
96 static void s3c2410wdt_keepalive(void)
97 {
98 spin_lock(&wdt_lock);
99 writel(wdt_count, wdt_base + S3C2410_WTCNT);
100 spin_unlock(&wdt_lock);
101 }
102
103 static void __s3c2410wdt_stop(void)
104 {
105 unsigned long wtcon;
106
107 wtcon = readl(wdt_base + S3C2410_WTCON);
108 wtcon &= ~(S3C2410_WTCON_ENABLE | S3C2410_WTCON_RSTEN);
109 writel(wtcon, wdt_base + S3C2410_WTCON);
110 }
111
112 static void s3c2410wdt_stop(void)
113 {
114 spin_lock(&wdt_lock);
115 __s3c2410wdt_stop();
116 spin_unlock(&wdt_lock);
117 }
118
119 static void s3c2410wdt_start(void)
120 {
121 unsigned long wtcon;
122
123 spin_lock(&wdt_lock);
124
125 __s3c2410wdt_stop();
126
127 wtcon = readl(wdt_base + S3C2410_WTCON);
128 wtcon |= S3C2410_WTCON_ENABLE | S3C2410_WTCON_DIV128;
129
130 if (soft_noboot) {
131 wtcon |= S3C2410_WTCON_INTEN;
132 wtcon &= ~S3C2410_WTCON_RSTEN;
133 } else {
134 wtcon &= ~S3C2410_WTCON_INTEN;
135 wtcon |= S3C2410_WTCON_RSTEN;
136 }
137
138 DBG("%s: wdt_count=0x%08x, wtcon=%08lx\n",
139 __func__, wdt_count, wtcon);
140
141 writel(wdt_count, wdt_base + S3C2410_WTDAT);
142 writel(wdt_count, wdt_base + S3C2410_WTCNT);
143 writel(wtcon, wdt_base + S3C2410_WTCON);
144 spin_unlock(&wdt_lock);
145 }
146
147 static inline int s3c2410wdt_is_running(void)
148 {
149 return readl(wdt_base + S3C2410_WTCON) & S3C2410_WTCON_ENABLE;
150 }
151
152 static int s3c2410wdt_set_heartbeat(int timeout)
153 {
154 unsigned long freq = clk_get_rate(wdt_clock);
155 unsigned int count;
156 unsigned int divisor = 1;
157 unsigned long wtcon;
158
159 if (timeout < 1)
160 return -EINVAL;
161
162 freq /= 128;
163 count = timeout * freq;
164
165 DBG("%s: count=%d, timeout=%d, freq=%lu\n",
166 __func__, count, timeout, freq);
167
168 /* if the count is bigger than the watchdog register,
169 then work out what we need to do (and if) we can
170 actually make this value
171 */
172
173 if (count >= 0x10000) {
174 for (divisor = 1; divisor <= 0x100; divisor++) {
175 if ((count / divisor) < 0x10000)
176 break;
177 }
178
179 if ((count / divisor) >= 0x10000) {
180 dev_err(wdt_dev, "timeout %d too big\n", timeout);
181 return -EINVAL;
182 }
183 }
184
185 tmr_margin = timeout;
186
187 DBG("%s: timeout=%d, divisor=%d, count=%d (%08x)\n",
188 __func__, timeout, divisor, count, count/divisor);
189
190 count /= divisor;
191 wdt_count = count;
192
193 /* update the pre-scaler */
194 wtcon = readl(wdt_base + S3C2410_WTCON);
195 wtcon &= ~S3C2410_WTCON_PRESCALE_MASK;
196 wtcon |= S3C2410_WTCON_PRESCALE(divisor-1);
197
198 writel(count, wdt_base + S3C2410_WTDAT);
199 writel(wtcon, wdt_base + S3C2410_WTCON);
200
201 return 0;
202 }
203
204 /*
205 * /dev/watchdog handling
206 */
207
208 static int s3c2410wdt_open(struct inode *inode, struct file *file)
209 {
210 if (test_and_set_bit(0, &open_lock))
211 return -EBUSY;
212
213 if (nowayout)
214 __module_get(THIS_MODULE);
215
216 expect_close = 0;
217
218 /* start the timer */
219 s3c2410wdt_start();
220 return nonseekable_open(inode, file);
221 }
222
223 static int s3c2410wdt_release(struct inode *inode, struct file *file)
224 {
225 /*
226 * Shut off the timer.
227 * Lock it in if it's a module and we set nowayout
228 */
229
230 if (expect_close == 42)
231 s3c2410wdt_stop();
232 else {
233 dev_err(wdt_dev, "Unexpected close, not stopping watchdog\n");
234 s3c2410wdt_keepalive();
235 }
236 expect_close = 0;
237 clear_bit(0, &open_lock);
238 return 0;
239 }
240
241 static ssize_t s3c2410wdt_write(struct file *file, const char __user *data,
242 size_t len, loff_t *ppos)
243 {
244 /*
245 * Refresh the timer.
246 */
247 if (len) {
248 if (!nowayout) {
249 size_t i;
250
251 /* In case it was set long ago */
252 expect_close = 0;
253
254 for (i = 0; i != len; i++) {
255 char c;
256
257 if (get_user(c, data + i))
258 return -EFAULT;
259 if (c == 'V')
260 expect_close = 42;
261 }
262 }
263 s3c2410wdt_keepalive();
264 }
265 return len;
266 }
267
268 #define OPTIONS (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE)
269
270 static const struct watchdog_info s3c2410_wdt_ident = {
271 .options = OPTIONS,
272 .firmware_version = 0,
273 .identity = "S3C2410 Watchdog",
274 };
275
276
277 static long s3c2410wdt_ioctl(struct file *file, unsigned int cmd,
278 unsigned long arg)
279 {
280 void __user *argp = (void __user *)arg;
281 int __user *p = argp;
282 int new_margin;
283
284 switch (cmd) {
285 case WDIOC_GETSUPPORT:
286 return copy_to_user(argp, &s3c2410_wdt_ident,
287 sizeof(s3c2410_wdt_ident)) ? -EFAULT : 0;
288 case WDIOC_GETSTATUS:
289 case WDIOC_GETBOOTSTATUS:
290 return put_user(0, p);
291 case WDIOC_KEEPALIVE:
292 s3c2410wdt_keepalive();
293 return 0;
294 case WDIOC_SETTIMEOUT:
295 if (get_user(new_margin, p))
296 return -EFAULT;
297 if (s3c2410wdt_set_heartbeat(new_margin))
298 return -EINVAL;
299 s3c2410wdt_keepalive();
300 return put_user(tmr_margin, p);
301 case WDIOC_GETTIMEOUT:
302 return put_user(tmr_margin, p);
303 default:
304 return -ENOTTY;
305 }
306 }
307
308 /* kernel interface */
309
310 static const struct file_operations s3c2410wdt_fops = {
311 .owner = THIS_MODULE,
312 .llseek = no_llseek,
313 .write = s3c2410wdt_write,
314 .unlocked_ioctl = s3c2410wdt_ioctl,
315 .open = s3c2410wdt_open,
316 .release = s3c2410wdt_release,
317 };
318
319 static struct miscdevice s3c2410wdt_miscdev = {
320 .minor = WATCHDOG_MINOR,
321 .name = "watchdog",
322 .fops = &s3c2410wdt_fops,
323 };
324
325 /* interrupt handler code */
326
327 static irqreturn_t s3c2410wdt_irq(int irqno, void *param)
328 {
329 dev_info(wdt_dev, "watchdog timer expired (irq)\n");
330
331 s3c2410wdt_keepalive();
332 return IRQ_HANDLED;
333 }
334
335
336 #ifdef CONFIG_CPU_FREQ
337
338 static int s3c2410wdt_cpufreq_transition(struct notifier_block *nb,
339 unsigned long val, void *data)
340 {
341 int ret;
342
343 if (!s3c2410wdt_is_running())
344 goto done;
345
346 if (val == CPUFREQ_PRECHANGE) {
347 /* To ensure that over the change we don't cause the
348 * watchdog to trigger, we perform an keep-alive if
349 * the watchdog is running.
350 */
351
352 s3c2410wdt_keepalive();
353 } else if (val == CPUFREQ_POSTCHANGE) {
354 s3c2410wdt_stop();
355
356 ret = s3c2410wdt_set_heartbeat(tmr_margin);
357
358 if (ret >= 0)
359 s3c2410wdt_start();
360 else
361 goto err;
362 }
363
364 done:
365 return 0;
366
367 err:
368 dev_err(wdt_dev, "cannot set new value for timeout %d\n", tmr_margin);
369 return ret;
370 }
371
372 static struct notifier_block s3c2410wdt_cpufreq_transition_nb = {
373 .notifier_call = s3c2410wdt_cpufreq_transition,
374 };
375
376 static inline int s3c2410wdt_cpufreq_register(void)
377 {
378 return cpufreq_register_notifier(&s3c2410wdt_cpufreq_transition_nb,
379 CPUFREQ_TRANSITION_NOTIFIER);
380 }
381
382 static inline void s3c2410wdt_cpufreq_deregister(void)
383 {
384 cpufreq_unregister_notifier(&s3c2410wdt_cpufreq_transition_nb,
385 CPUFREQ_TRANSITION_NOTIFIER);
386 }
387
388 #else
389 static inline int s3c2410wdt_cpufreq_register(void)
390 {
391 return 0;
392 }
393
394 static inline void s3c2410wdt_cpufreq_deregister(void)
395 {
396 }
397 #endif
398
399
400
401 /* device interface */
402
403 static int __devinit s3c2410wdt_probe(struct platform_device *pdev)
404 {
405 struct resource *res;
406 struct device *dev;
407 unsigned int wtcon;
408 int started = 0;
409 int ret;
410 int size;
411
412 DBG("%s: probe=%p\n", __func__, pdev);
413
414 dev = &pdev->dev;
415 wdt_dev = &pdev->dev;
416
417 /* get the memory region for the watchdog timer */
418
419 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
420 if (res == NULL) {
421 dev_err(dev, "no memory resource specified\n");
422 return -ENOENT;
423 }
424
425 size = resource_size(res);
426 wdt_mem = request_mem_region(res->start, size, pdev->name);
427 if (wdt_mem == NULL) {
428 dev_err(dev, "failed to get memory region\n");
429 ret = -ENOENT;
430 goto err_req;
431 }
432
433 wdt_base = ioremap(res->start, size);
434 if (wdt_base == NULL) {
435 dev_err(dev, "failed to ioremap() region\n");
436 ret = -EINVAL;
437 goto err_req;
438 }
439
440 DBG("probe: mapped wdt_base=%p\n", wdt_base);
441
442 wdt_irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
443 if (wdt_irq == NULL) {
444 dev_err(dev, "no irq resource specified\n");
445 ret = -ENOENT;
446 goto err_map;
447 }
448
449 ret = request_irq(wdt_irq->start, s3c2410wdt_irq, 0, pdev->name, pdev);
450 if (ret != 0) {
451 dev_err(dev, "failed to install irq (%d)\n", ret);
452 goto err_map;
453 }
454
455 wdt_clock = clk_get(&pdev->dev, "watchdog");
456 if (IS_ERR(wdt_clock)) {
457 dev_err(dev, "failed to find watchdog clock source\n");
458 ret = PTR_ERR(wdt_clock);
459 goto err_irq;
460 }
461
462 clk_enable(wdt_clock);
463
464 if (s3c2410wdt_cpufreq_register() < 0) {
465 printk(KERN_ERR PFX "failed to register cpufreq\n");
466 goto err_clk;
467 }
468
469 /* see if we can actually set the requested timer margin, and if
470 * not, try the default value */
471
472 if (s3c2410wdt_set_heartbeat(tmr_margin)) {
473 started = s3c2410wdt_set_heartbeat(
474 CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
475
476 if (started == 0)
477 dev_info(dev,
478 "tmr_margin value out of range, default %d used\n",
479 CONFIG_S3C2410_WATCHDOG_DEFAULT_TIME);
480 else
481 dev_info(dev, "default timer value is out of range, "
482 "cannot start\n");
483 }
484
485 ret = misc_register(&s3c2410wdt_miscdev);
486 if (ret) {
487 dev_err(dev, "cannot register miscdev on minor=%d (%d)\n",
488 WATCHDOG_MINOR, ret);
489 goto err_cpufreq;
490 }
491
492 if (tmr_atboot && started == 0) {
493 dev_info(dev, "starting watchdog timer\n");
494 s3c2410wdt_start();
495 } else if (!tmr_atboot) {
496 /* if we're not enabling the watchdog, then ensure it is
497 * disabled if it has been left running from the bootloader
498 * or other source */
499
500 s3c2410wdt_stop();
501 }
502
503 /* print out a statement of readiness */
504
505 wtcon = readl(wdt_base + S3C2410_WTCON);
506
507 dev_info(dev, "watchdog %sactive, reset %sabled, irq %sabled\n",
508 (wtcon & S3C2410_WTCON_ENABLE) ? "" : "in",
509 (wtcon & S3C2410_WTCON_RSTEN) ? "" : "dis",
510 (wtcon & S3C2410_WTCON_INTEN) ? "" : "en");
511
512 return 0;
513
514 err_cpufreq:
515 s3c2410wdt_cpufreq_deregister();
516
517 err_clk:
518 clk_disable(wdt_clock);
519 clk_put(wdt_clock);
520
521 err_irq:
522 free_irq(wdt_irq->start, pdev);
523
524 err_map:
525 iounmap(wdt_base);
526
527 err_req:
528 release_resource(wdt_mem);
529 kfree(wdt_mem);
530
531 return ret;
532 }
533
534 static int __devexit s3c2410wdt_remove(struct platform_device *dev)
535 {
536 s3c2410wdt_cpufreq_deregister();
537
538 release_resource(wdt_mem);
539 kfree(wdt_mem);
540 wdt_mem = NULL;
541
542 free_irq(wdt_irq->start, dev);
543 wdt_irq = NULL;
544
545 clk_disable(wdt_clock);
546 clk_put(wdt_clock);
547 wdt_clock = NULL;
548
549 iounmap(wdt_base);
550 misc_deregister(&s3c2410wdt_miscdev);
551 return 0;
552 }
553
554 static void s3c2410wdt_shutdown(struct platform_device *dev)
555 {
556 s3c2410wdt_stop();
557 }
558
559 #ifdef CONFIG_PM
560
561 static unsigned long wtcon_save;
562 static unsigned long wtdat_save;
563
564 static int s3c2410wdt_suspend(struct platform_device *dev, pm_message_t state)
565 {
566 /* Save watchdog state, and turn it off. */
567 wtcon_save = readl(wdt_base + S3C2410_WTCON);
568 wtdat_save = readl(wdt_base + S3C2410_WTDAT);
569
570 /* Note that WTCNT doesn't need to be saved. */
571 s3c2410wdt_stop();
572
573 return 0;
574 }
575
576 static int s3c2410wdt_resume(struct platform_device *dev)
577 {
578 /* Restore watchdog state. */
579
580 writel(wtdat_save, wdt_base + S3C2410_WTDAT);
581 writel(wtdat_save, wdt_base + S3C2410_WTCNT); /* Reset count */
582 writel(wtcon_save, wdt_base + S3C2410_WTCON);
583
584 printk(KERN_INFO PFX "watchdog %sabled\n",
585 (wtcon_save & S3C2410_WTCON_ENABLE) ? "en" : "dis");
586
587 return 0;
588 }
589
590 #else
591 #define s3c2410wdt_suspend NULL
592 #define s3c2410wdt_resume NULL
593 #endif /* CONFIG_PM */
594
595
596 static struct platform_driver s3c2410wdt_driver = {
597 .probe = s3c2410wdt_probe,
598 .remove = __devexit_p(s3c2410wdt_remove),
599 .shutdown = s3c2410wdt_shutdown,
600 .suspend = s3c2410wdt_suspend,
601 .resume = s3c2410wdt_resume,
602 .driver = {
603 .owner = THIS_MODULE,
604 .name = "s3c2410-wdt",
605 },
606 };
607
608
609 static char banner[] __initdata =
610 KERN_INFO "S3C2410 Watchdog Timer, (c) 2004 Simtec Electronics\n";
611
612 static int __init watchdog_init(void)
613 {
614 printk(banner);
615 return platform_driver_register(&s3c2410wdt_driver);
616 }
617
618 static void __exit watchdog_exit(void)
619 {
620 platform_driver_unregister(&s3c2410wdt_driver);
621 }
622
623 module_init(watchdog_init);
624 module_exit(watchdog_exit);
625
626 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>, "
627 "Dimitry Andric <dimitry.andric@tomtom.com>");
628 MODULE_DESCRIPTION("S3C2410 Watchdog Device Driver");
629 MODULE_LICENSE("GPL");
630 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
631 MODULE_ALIAS("platform:s3c2410-wdt");
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